For one example of a mobile communication system to which the contents proposed by the present specification are applicable, 3GPP LTE (3rd generation partnership project long term evolution: hereinafter abbreviated LTE) communication system and LTE-Advanced (hereinafter abbreviated LTE-A) communication system are schematically described as follows.
At least one or more cells exist in a single base station (or eNode B). The cell sets a single carrier to one of bandwidths including 1.25 MHz, 2.5 MHz, 5 MHz, 10 MHz, 15 MHz, 20 MHz and the like and then provides DL/UL (downlink/uplink) service to a plurality of user equipments. In doing so, different cells may be configured to provide different bandwidths, respectively. A base station (or eNode B) transmits downlink (DL) scheduling information for downlink (DL) data to inform a corresponding user equipment of time/frequency region for transmitting data, coding, data size, HARQ (hybrid automatic repeat and request) related information and the like. The base station also transmits UL scheduling information for uplink (UL) data to the corresponding user equipment to indicate time/frequency region available for the corresponding user equipment, coding, data size, HARQ related information and the like. Moreover, an interface for user or control traffic transmission may be usable between base stations (or eNode Bs).
Wireless communication technology has been developed up to LTE based on WCDMA (wideband code division multiple access). Yet, the demand and expectation of users and service providers has increased persistently. Moreover since many ongoing efforts are made to research and develop other radio access technologies, the demand for new technology evolution is increasing to have competitive power in the future. In particular, cost reduction per bit, service availability expansion, flexible frequency band use, simple-structured open interface, reasonable power consumption of user equipment and the like are required.
Recently, ongoing standardization of the next technology of LTE is performed by 3GPP. Such technology shall be named LTE-A in the present specification. Big differences between LTE system and LTE-A system may include a system bandwidth difference and an adoption of a relay node.
The goal of LTE-A system is to support maximum 100 MZ wideband. To this end, LTE-A system uses carrier aggregation or bandwidth aggregation to achieve the wideband using a plurality of frequency blocks. According to the carrier aggregation, a plurality of frequency blocks are used as one wide logical frequency band to use wider frequency band. And, a bandwidth of each of the frequency blocks may be defined based on a bandwidth of a system block used by LTE system. And, each of the frequency blocks is transmitted using a component carrier.
As the LTE-A system of the next generation communication system adopts the carrier aggregation technology, a user equipment is able to receive a signal from a base station or relay node of a system supportive of a plurality of carriers.
However, in case of attempting to transmit/receive data efficiently by adapting to a change of a wireless environment in a system supportive of a plurality of carriers, it may be necessary to monitor a state of each of a plurality of the carriers frequently. Therefore, the demand for a method of transmitting/receiving a channel state information on each carrier, i.e., a method of effectively transmitting a feedback on each channel state in a manner fit for a limited frame is rising.